package com.tfb.service.utility;

import static com.tfb.service.utility.JsonUtil.UTF8;
import java.util.UUID;
import java.util.Map;
import java.util.HashMap;
import java.util.Formatter;
import java.security.MessageDigest;
import org.apache.log4j.Logger;

public class WechatSign {

    private static final Logger log = Logger.getLogger(WechatSign.class);

    public static void main(String[] args) {
        String jsapi_ticket = "jsapi_ticket";

        // 注意 URL 一定要动态获取，不能 hardcode
        String url = "http://example.com";
        Map<String, String> ret = sign(jsapi_ticket, url);
        for (Map.Entry entry : ret.entrySet()) {
            System.out.println(entry.getKey() + ", " + entry.getValue());
        }
    }

    public static Map<String, String> sign(String jsapi_ticket, String url) {
        Map<String, String> ret = new HashMap<>();
        String nonce_str = create_nonce_str();
        String timestamp = create_timestamp();
        String string1;
        String signature = "";

        //注意这里参数名必须全部小写，且必须有序
        string1 = "jsapi_ticket=" + jsapi_ticket
                  + "&noncestr=" + nonce_str
                  + "&timestamp=" + timestamp
                  + "&url=" + url;
        System.out.println(string1);

        try {
            MessageDigest crypt = MessageDigest.getInstance("SHA-1");
            crypt.reset();
            crypt.update(string1.getBytes(UTF8));
            signature = byteToHex(crypt.digest());
        } catch (Exception e) {
            log.error(Utils.getFullException(e));
            return null;
        }

        ret.put("appId", AppConst.APP_ID);
        ret.put("url", url);
        ret.put("jsapi_ticket", jsapi_ticket);
        ret.put("nonceStr", nonce_str);
        ret.put("timestamp", timestamp);
        ret.put("signature", signature);

        return ret;
    }

    private static String byteToHex(final byte[] hash) {
        String result;
        try (Formatter formatter = new Formatter()) {
            for (byte b : hash) {
                formatter.format("%02x", b);
            }
            result = formatter.toString();
        }
        return result;
    }

    private static String create_nonce_str() {
        return UUID.randomUUID().toString();
    }

    private static String create_timestamp() {
        return Long.toString(System.currentTimeMillis() / 1000);
    }
}
